Japanese Laid-open Patent Application No. 2002-107787 suggests a camera system which decides whether to activate a function to reduce the shaking or not in accordance with the lens unit as attached to the camera main body. Japanese Laid-open Patent Application No. 2003-121913 suggests a camera system where data on image distortion of a taking lens of the lens unit as attached to the camera main body is sent to the camera main body through a lens unit interface.
Such a camera system conventionally has a problem that it is difficult for beginners to see if an attachment is connectable to a camera main body, especially when the beginner wants to buy the attachment. It will be a great problem if a user has bought an attachment that is not connectable to a camera main body that the user already has. Furthermore, even for those skilled in photography who can see the compatibility of an attachment to a camera main body, i.e., the capability of connecting the attachment to the camera main body, it is difficult to see instantly and exactly how the attachment works in connection with the camera main body.
Japanese Laid-open Patent Application No. Hei 8-172561 suggests a camera system wherein a plug-in unit having an imaging device and an imaging optical system integrated therein is removably attachable to a camera main body. When the camera head is attached to the camera main body, data on the plug-in unit is transmitted to the camera main body, so as to enable capturing images as formed through the imaging optical system of the plug-in unit. According to this camera system, it becomes possible to change the imaging optical system, namely the taking lens, just by attaching the plug-in unit to the camera main body. So the camera system of this prior art can be very easy to handle, allowing unskilled photographers to interchange the taking lens without failure.
Same kinds of camera systems have been known for example from Japanese Laid-open Patent Application No. 2000-175089, wherein a camera head having an imaging optical system and an imaging device is removably attachable to a camera main body, which receives image signals from the attached camera head, to process the image signal.
These camera systems would meet any customer's needs if there are a wide variety of camera heads and a wide variety of camera main bodies that are compatible with any of those camera heads.
However, if there is any difference in electric configuration between the camera head and the camera main body, the camera head would not work in connection with the camera main body. To avoid this problem, a method of checking if an interchangeable lens is compatible with a camera main body with respect to their electric configurations has been suggested for example in Japanese Laid-open Patent Application No. 2003-228115, though the lens attachment mentioned in this prior art is not provided with an imaging device.
According to the method of this prior art, each time when any of a variety of interchangeable lens units is connected to any of a variety of camera main bodies, a controller of this camera main body checks if the electric configuration of the attached lens unit, such as output current and output voltage, fit the electric configuration of the camera main body, such as input current and input voltage.
The method suggested in the above prior art enables the controller of the camera main body to make judgment on whether the camera main body can execute suitable processing for the interchangeable lens that is attached to the camera main body.
Recently, such a camera system has been suggested that consists of a camera head having an imaging optical system and an imaging device and a camera main body, wherein image signals produced through the imaging device are transferred to the camera main body through image communication interfaces provided respectively in the camera head and the camera main body. The transferred image signals are processed in a signal processing section of the camera main body. In such a camera system, it is necessary to check if the image communication interface of the camera head is adaptable to the image communication interface of the camera main body. The camera system disclosed in the above mentioned Japanese Laid-open Patent Application No. 2003-228115 does not check the compatibility between the image communication interfaces of the camera head and the camera main body.